The present invention relates to electrical fuse blocks for mounting in cabinets and having a forwardly-extending, rotary disconnect operator that may engage a handle on the cabinet door when the cabinet door is closed, and in particular to an improvement in such a fuse block that reduces the chance of accidental operation of the disconnect operator when the cabinet door is open.
Referring to FIG. 1, a standard fuse block 10 of the prior art may receive fuse cartridges 12 along its front face and may attach at its rear face to the rear wall 14 of a metal cabinet 16.
Input terminals along the top of the fuse block 10 may receive wires 18 which connect independently to one side of each fuse cartridge 12, the latter which interconnect wires 18 to wires 20 attached to output terminals along the bottom of the fuse cartridge 12. The wires 18, for example, may be connected to a source of three-phase power and the wires 20, for example, may be connected to a motor or other piece of equipment.
The fuse block 10 may incorporate a disconnect mechanism (not shown) serving to electrically disconnect the wires 18 from the respective fuse cartridges 12. The disconnect may be controlled by a rotary operator 22 along one side of the fuse block 12 and extending in an orientation perpendicular to the rear wall 14 of the cabinet 16 toward an open face of the cabinet 16.
The open face of the cabinet may be covered by a door 24 attached by hinges to one side of the cabinet 16. The door 24 may support a captively mounted rotary handle 26 having an inwardly extending shaft 28.
Referring now to FIG. 2, the handle 26 may include a shaft 28 extending inwardly through an opening in the door 24 and having retaining flanges 30 for retaining it rotatively within that opening.
When the door 24 is closed about the cabinet 16, the shaft 28 of the handle 26 may engage the outermost end of the rotary operator 22 allowing the rotary operator to be operated by the handle 26 when the door 24 is closed on the cabinet 16. Specifically, an inwardly facing end of the shaft 28 may include a keyway 32 receiving a rectangular end of the rotary operator 22 and a pin 34 extending perpendicularly through the rotary operator. Turning the handle 26, turns the rotary operator 22 electrically disconnecting or connecting power to wires 20.
Referring again to FIG. 1, while the handle 26 allows disconnection of power to wires 20, the door 24 on the cabinet 16 is closed. Once the door 24 is open, power may be inadvertently reconnected by counter rotation of the rotary operator 22 which is how exposed.
The present invention modifies a standard fuse block to allow it to sense the position of the door of the cabinet and lock its disconnect in the open position to prevent inadvertent connection of power when the cabinet door is open. The locking of the disconnect may be manually overridden if it is necessary to reconnect power when the cabinet door is open.
Specifically, the present invention provides a side mounted lockout positioned proximate to the side face of the fuse block and having a sensing arm having a first end positioned near the outer end of the of the fuse block""s rotary operator. When the door is closed, the sensing arm is pressed inward by engagement of the outer end rotary operator and the door mounted handle. An operator lock communicates with the sensor arm and the rotary operator to lock rotation of the rotary operator except when the sensing arm is depressed.
Thus, it is one object of the invention to provide a method of locking fuse blocks of this type against inadvertent actuation when the door is open.
It is another object of the invention to provide a locking mechanism that will work with a variety of different cabinet types. Locating the door sensor near the operator, allows the door handle, which necessarily is positioned to engage the rotary operator, to provide the necessary actuation. Modifications to the door or a particular location or orientation of the fuse block within the cabinet are not required so long as the operator of the fuse block properly engages the door handle.
The sensing arm may be a sleeve slidably fitting over the rotary operator.
Thus, it is another object of the invention to provide for a simple sensing mechanism that is fully supported by the sensing arm to be in alignment with the actuating door handle.
The sleeve may include at least one radial extension arm abutting the portion of the door mounted handle when the outer end of the rotary operator is engaged with the portion of the door mounted handle.
Thus, it is another object of the invention to provide a door sensor that works with a variety of different door mounted handles so long as some part of the door handle engages the radial arm.
The radial extension arm may extend over the front face of the fuse block when the rotary operator is rotated to connect power. Conversely, the radial extension arm may extend along the side face of the fuse block and not over the front face when the rotary arm is rotated to disconnect the fuse to the power connections.
Thus it is another object of the invention to provide a visual indication of a connected fuse block, and alternatively, to prevent interference with removal of the fuses by the radial arm when the fuse block is disconnected.
The operator lock may include a collar engaging the rotary operator and having at least one tooth captured by a stop communicating with the sensing arm to be retracted when the sensing arm is depressed inward.
Thus, it is another object of the invention to provide a locking mechanism that may work with existing fuse block designs by engagement of a collar with the normally rectangular shaft of the rotary operator.
The stop may be a slider plate mounted slidably to a support plate fixed with respect to the fuse block, the slider plate sliding along an outwardly extending axis.
It is another object of the invention to provide a locking mechanism that may fit closely adjacent to the fuse block so as not to increase the amount of space required within the cabinet for the fuse block.
The slider plate and mounting plate may have holes sized to receive the shank of a padlock and aligned when the operator is in the position of disconnecting the fuse.
Thus, it is another object of the invention to provide for a positive lockout of the fuse block that cannot be defeated by opening of the cabinet door or manipulating the mechanical operator lock.
These particular objects and advantages may apply to only some embodiments falling within the claims, and thus do not define the scope of the invention.